Core-pulling mechanism and injection mold with the same

Abstract

A core-pulling mechanism for pulling a slide core and a threaded-pin core in an injection mold includes a hinge shaft having two ends with polygonal cross-section, an shaft sleeve assembled with a rear of the hinge shaft, a baffle block having axial through opening allowing the hinge shaft to pass through and rotate therein, a slider having a through hole for receiving the baffle block and a semi-closed transmission hole defined in a rear wall, a transmission shaft assembled in the transmission hole and fixed to the slider, and a guide block. The baffle block and the guide block have inclined guiding bulges and inclined guiding grooves engaging with each other to guide the baffle block to slide. While the transmission shaft drives the slider to move backward, the hinge shaft following with the slider move backward and slide in the shaft sleeve, thus, the distance of the backward movement of the cores pulled by the core-pulling mechanism is not limited.

1. A core-pulling mechanism for pulling a slide core and a threaded-pin core in an injection mold, the slide core defining a mold hole, the threaded-pin core having an external threaded end at a front end thereof and a flange at a rear end thereof, and a semi-closed polygonal hole defined in the rear end thereof, the external threaded end of the threaded-pin core inserting into the mold hole to define an internal-thread molding cavity there-between, the core-pulling mechanism comprising:
 a hinge shaft having a front end and an opposite rear end with polygonal cross section respectively, the front end of the hinge shaft being shaped and dimensioned for mating with the polygonal hole of the threaded-pin core; 
 a shaft sleeve having a polygonal aperture extending there-through, the polygonal aperture being shaped and dimensioned to mate with the rear end of the hinge shaft so that the hinge shaft rotates with the shaft sleeve when the shaft sleeve is driven by a first external driving device; 
 a baffle block having an axial through opening to allow the hinge shaft to pass there-through and rotate therein; 
 a slider, a through hole being defined in the slider, a semi-closed transmission hole being defined in a rear wall of the slider, an inlay cavity being defined in a front wall of the slider, a front portion of the baffle block being inserted in the through hole and withstanding the flange of the threaded-pin core, the front end of the hinge shaft passing through the axial through opening and the through hole and inserting into the polygonal hole of the threaded-pin core so that the threaded-pin core rotates with the hinge shaft, said slide core being infixed to the inlay cavity of the slider; 
 a transmission shaft mounted in the transmission hole of the slider to drive the slider and the slide core backward when the transmission shaft is driven by a second external driving device; and 
 a guide block, the guide block and the baffle block defining an inclined guiding groove and an inclined guiding bulge engaging with each other to guide the baffle block to slide. 
 
   
   
     2. The core-pulling mechanism as claimed in  claim 1 , wherein said baffle block further comprises a baffle body and two supporting arms protruding from a rear of the baffle body, the two supporting arms are separated from each other to define an interval space to allow the hinge shaft to pass through, a pair of first inclined guiding bulges are protruded from outer sides of rear ends of the two supporting arms, said guide block further comprises a guide body and two clips protruded forward from the guide body, and a pair of first inclined guiding grooves is defined in inner walls of the two clips corresponding to the pair of first inclined guiding bulges. 
   
   
     3. The core-pulling mechanism as claimed in  claim 2 , wherein a pair of second inclined guiding grooves is defined in front of the first inclined guiding bulges of the baffle block, a pair of second inclined guiding bulges is protruded from the inner walls of the two clips in front of the first inclined guiding grooves of the guide block for engaging with the pair of second inclined guiding grooves. 
   
   
     4. The core-pulling mechanism as claimed in  claim 2 , wherein the inner wall of the through hole of the slider forms a step, the baffle body is received in the through hole and moves in front of the step, the step withstands the rear wall of the baffle body. 
   
   
     5. The core-pulling mechanism as claimed in  claim 2 , wherein a middle portion of the hinge shaft is circular shape, and a corresponding portion of the axial through opening of the baffle block is shaped to match with the circular protrusion hinge shaft and allow the hinge shaft to rotate therein. 
   
   
     6. The core-pulling mechanism as claimed in  claim 5 , further comprising a wear-resisting block fixed to the rear of the slider and abutting against the rear wall of the circular portion of the hinge shaft, wherein a cutting hole is defined in the wear-resisting block to allow said two supporting arms to pass through. 
   
   
     7. The core-pulling mechanism as claimed in  claim 1 , wherein the cross section of said front end of the hinge shaft is rectangular, and the cross section of said polygonal hole is rectangular. 
   
   
     8. The core-pulling mechanism as claimed in  claim 1 , wherein the cross section of said rear end of the hinge shaft is rectangular, and the cross section of the polygonal aperture is rectangular. 
   
   
     9. The core-pulling mechanism as claimed in  claim 1 , wherein the front portion of the axial through opening is ladder-shaped for receiving the flange of the threaded-pin core. 
   
   
     10. The core-pulling mechanism as claimed in  claim 1 , further comprising a pair of springs and a pair of receiving holes defined in a front wall of the baffle block for receiving the pair of springs. 
   
   
     11. An injection mold for molding a plastic article with an internal threaded hole and a cave, comprising:
 an upper mold having female mold cores therein; 
 a lower mold having male mold cores therein, the lower mold being disposed under the upper mold; 
 a slide core disposed in the lower mold for forming said cave of the plastic article, a mold hole being defined in the slide core; 
 a threaded-pin core having an external threaded end at a front end thereof and a flange at a rear end thereof, and a semi-closed polygonal hole defined in the rear end thereof, the external threaded end of the threaded-pin core inserting into the mold hole to define an internal-thread molding cavity there-between for molding said internal threaded hole, the slide core, the threaded-pin core, the upper mold and the lower mold being closed to define a mold cavity for molding said plastic article; and 
 a core-pulling mechanism for pulling said slide core and said threaded-pin core, the core-pulling mechanism comprising: 
 a hinge shaft having a front end and an opposite rear end with polygonal cross section respectively, the front end of the hinge shaft being shaped and dimensioned for mating with the polygonal hole of the threaded-pin core; 
 a shaft sleeve having a polygonal aperture extending there-through, the polygonal aperture being shaped and dimensioned to mate with the rear end of the hinge shaft so that the hinge shaft rotates with the shaft sleeve when the shaft sleeve is driven by a first external driving device; 
 a baffle block having an axial through opening to allow the hinge shaft to pass there-through and rotate therein; 
 a slider disposed in the lower mold, a through hole being defined in the slider, a semi-closed transmission hole being defined in a rear wall of the slider, an inlay cavity being defined in a front wall of the slider, a front portion of the baffle block being inserted in the through hole and withstanding the flange of the threaded-pin core, the front end of the hinge shaft passing through the axial through opening and the through hole and inserting into the polygonal hole of the threaded-pin core so that the threaded-pin core rotates with the hinge shaft, said slide core being infixed to the inlay cavity of the slider; 
 a transmission shaft mounted in the transmission hole of the slider to drive the slider and the slide core backward when the transmission shaft is driven by a second external driving device; and 
 a guide block fixed to the upper mold, the guide block and the baffle block defining an inclined guiding groove and an inclined guiding bulge engaging with each other to guide the baffle block to slide. 
 
   
   
     12. The injection mold as claimed in  claim 11 , wherein said baffle block further comprises a baffle body and two supporting arms protruding from a rear of the baffle body, the two supporting arms are separated from each other to define an interval space to allow the hinge shaft to pass through, a pair of first inclined guiding bulges are protruded from outer sides of rear ends of the two supporting arms, said guide block further comprises a guide body and two clips protruded forward from the guide body, and a pair of first inclined guiding grooves is defined in inner walls of the two clips corresponding to the pair of first inclined guiding bulges. 
   
   
     13. The injection mold as claimed in  claim 12 , wherein a pair of second inclined guiding grooves is defined in front of the first inclined guiding bulges of the baffle block, a pair of second inclined guiding bulges is protruded from the inner walls of the two clips in front of the first inclined guiding grooves of the guide block for engaging with the pair of second inclined guiding grooves. 
   
   
     14. The injection mold as claimed in  claim 12 , wherein the inner wall of the through hole of the slider forms a step, the baffle body is received in the through hole and moves in front of the step, the step withstands the rear wall of the baffle body. 
   
   
     15. The injection mold as claimed in  claim 12 , wherein a middle portion of the hinge shaft is circular shape, and a corresponding portion of the axial through opening of the baffle block is shaped to match with the circular protrusion hinge shaft and allow the hinge shaft to rotate therein. 
   
   
     16. The injection mold as claimed in  claim 15 , further comprising a wear-resisting block fixed to the rear of the slider and abutting against the rear wall of the circular portion of the hinge shaft, wherein a cutting hole is defined in the wear-resisting block to allow said two supporting arms to pass through. 
   
   
     17. The injection mold as claimed in  claim 11 , wherein the cross section of said front end of the hinge shaft is rectangular, and the cross section of said polygonal hole is rectangular. 
   
   
     18. The injection mold as claimed in  claim 11 , wherein the cross section of said rear end of the hinge shaft is rectangular, and the cross section of the polygonal aperture is rectangular. 
   
   
     19. The injection mold as claimed in  claim 11 , wherein said slide core further comprises an rectangular insert body and a inlay block, said insert body is extended from a portion of the inlay block, said mold hole is defined in the other portion of the inlay block. 
   
   
     20. The injection mold as claimed in  claim 11 , wherein the front portion of the axial through opening is ladder-shaped for receiving the flange of the threaded-pin core.